Add Javascript-Heavy tags for system health stories with heavy uses of JS

tools/perf/page_sets/system_health/background_stories.py

Index: tools/perf/page_sets/system_health/background_stories.py
diff --git a/tools/perf/page_sets/system_health/background_stories.py b/tools/perf/page_sets/system_health/background_stories.py
index 5bdf2617312364c57b0df5bd1847f7903733c829..b55eb7006ca7cddf297dd7e3f6364264aa9f4b24 100644
--- a/tools/perf/page_sets/system_health/background_stories.py
+++ b/tools/perf/page_sets/system_health/background_stories.py
@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 from page_sets.system_health import platforms
+from page_sets.system_health import story_tags
 from page_sets.system_health import system_health_story
 from page_sets.system_health.loading_stories import LoadGmailMobileStory
 
@@ -46,6 +47,7 @@ class BackgroundNytimesMobileStory(_BackgroundStory):
   NAME = 'background:news:nytimes'
   URL = 'http://www.nytimes.com/2016/10/04/us/politics/vice-presidential-debate.html?_r=0'
   SUPPORTED_PLATFORMS = platforms.MOBILE_ONLY
+  TAGS = [story_tags.JAVASCRIPT_HEAVY]
 
   def _DidLoadDocument(self, action_runner):
     # Dismiss the 'You have n free articles' message.